This invention relates to the hot grinding of metal stock and specifically to an abrasive belt backing material adapted for use in hot grinding applications.
Continuous casting of slab, thin plate and strip has been expanding significantly in recent years with many companies, especially in the United States and in Europe developing proprietary positions in casting equipment and technologies. Typically the metal casting is ground after it has been cooled and can easily be handled. It has been pointed out however that this is not very logical since the metal, upon cooling, becomes rapidly covered with a coating of oxide and scale which can not readily be removed. Thus from a purely theoretical point of view a metal should be more easily ground when it is hot. Moreover the time taken for the cooling is essentially wasted. It has therefore been proposed to grind the metal when it is hot and suitable machinery and techniques for doing this are set out in European Patent Application 435,897.
However it is found that existing belts, though usable for such applications, fail prematurely as a result of backing failure at the temperatures encountered. It has now been found that this failure mode is often associated not with the wearing out of the abrasive but with excessive elongation of the belt during grinding, where the ambient temperature in the grinding environment can be several hundred degrees Centigrade. This elongation can make the tension on the belt vary and can result in slipping on the rolls on which it is carried or perhaps uneven pressure across the width of the belt where the expansion is uneven.
The present invention provides a coated abrasive belt built upon a backing that is particularly well adapted for the very difficult working conditions encountered in this application. As a result the working life is greatly extended and the quality of grinding is improved.